Peavy rage158

This forum is for talking about all kinds of Peavey guitar amplifiers.
Post Reply
Ketaylor
New Member
Posts: 1
Joined: Tue Jan 07, 2025 11:04 pm

Peavy rage158

Post by Ketaylor » Tue Jan 07, 2025 11:08 pm

What is the output voltage for the power transformer. The part # is 705-28729. The transformer is bad, discontinued and Peavy won't give me the information to locate one aftermarket....

rogue777
Member
Posts: 317
Joined: Mon Sep 14, 2009 7:07 pm

Re: Peavy rage158

Post by rogue777 » Fri Jan 10, 2025 8:23 pm

What is the wrong with the transformer you have?
>>>>>>>>>>>
The main power supply voltage is +28 Vdc. The voltage from the xformer secondary is rectified by a full wave bridge and stored on a large value filter cap. This is essentially the peak voltage. So what is the rms voltage on the secondary of the xformer. It’s 28 Vpk x .707 = ?
You can use a calculator. I’ll use my slide rule. I get about 20 V, which would be the secondary voltage.

On the back of the amp, is says 40 Watts as the power consumption. Due to the equilibrium of power in a transformer, Pwr pri = Pwr sec, the secondary current would be (using formula: Pwr = Voltage * Current), solving for current,,,,,, slide rule says 2 amps. (40 Watts/20 Volts = 2 Amps).

Does this help and does it sound right? You got to get the right size part.
Maybe you can find an old Rage that’s broken and use that transformer.

https://www.thetubestore.com/lib/thetub ... ematic.pdf [/url]

User avatar
Pappy B
Member
Posts: 899
Joined: Sun Jan 31, 2016 2:30 pm

Re: Peavy rage158

Post by Pappy B » Sat Jan 11, 2025 10:32 am

Not trying to insult you, but how did you determine the transformer is bad?
The more I learn the more I realize how much I don't know.

Post Reply